Many siding panels for buildings are generally of aluminum or vinyl construction; they are most often made to a standard eight-inch width, and in either a single- or double-lap configuration, the latter commonly being referred to as a "4/4" or "double-4" panel. It is now conventional to back such panels with a backerboard made of a rigid cellular synthetic resinous material, such as expanded polystyrene, for thermal insulation as well as to provide structural support for the panels, which are susceptible to denting and bending. It is a standard practice to incorporate a moisture vapor barrier sheeting (normally aluminum foil) into the wall structure, and, when a backerboard is employed, it is advantageous to laminate the barrier sheeting directly thereto during the manufacturing procedure, rather than in the field. Doing so saves time and labor, and significantly reduces tearing and wrinkling of the foil, as often occurs when it is applied separately during the siding application procedure.
Most desirably, the installed backerboard will closely follow the internal contour of the vinyl or aluminum panel, since this provides maximum support and insulation while avoiding the formation of unduly large pockets of air space between the panel and the backerboard. It is relatively easy to achieve such a relationship in a single lap panel, simply by utilizing a backerboard of corresponding width. While, in a similar manner, each horizontal wall section of a double lap panel could be backed with a backerboard of the same width, such an approach would entail obvious disadvantages. For example, doing so would require that a variety of sizes of backerboard be stocked and transported; it would involve excessive handling and manipulation for application to the panel and to the wall structure; and it would make it impractical to provide a continuous moisture barrier between the pieces of backerboard within a single panel.
Certain of the foregoing factors have previously been appreciated, and backerboard constructions have been proposed in the art in an effort to achieve the recognized advantages. For example, in U.S. Pat. Nos. 4,033,802 and 4,081,939, Culpepper Jr. et al. describe a backerboard comprised of two elongated members fabricated from an insulating foam material and fastened together along their overlapped longitudinal edges. This construction presents a longitudinal edge on one of the members for abutment against the inner surface of the step that connects the two wall portions of the panel, and this is said to minimize the dead air space that results when the prior art backerboard structure, identified by the patentees, is used; it is also said to maximize the level of support for the longitudinal step of the panel. However, because the construction described by Culpepper, Jr., et al. is tailored to a specific configuration of double-lap siding panel, its utility is limited; moreover, manufacture of the backerboard described is not as facile, practical, or economical as it might be.
Accordingly, it is a primary object of the present invention to provide a novel dual-purpose backerboard, and a novel method for producing the same, which backerboard can readily be used in assembly with either a single-lap or a double-lap configuration of siding panel.
It is also an object of the invention to provide such a backerboard and method wherein the continuity of the moisture barrier sheeting laminated thereto is not disrupted, regardless of whether the backerboard is utilized in its single- or double-lap configuration.
Another object of the invention is to provide a method for the production of an assembly of a backerboard with a double-lap siding panel, and the novel assembly so produced.
Yet another object of the invention is to provide a novel backerboard construction which is facile and relatively inexpensive to produce, is convenient to install, and is highly effective for its intended purposes.